Safe methods vs unsafe methods in Rest API - Practice Questions

Challenge - 5 Problems

🧠 Conceptual

intermediate

Which HTTP method is considered safe?

In REST APIs, safe methods are those that do not change server data. Which of the following HTTP methods is safe?

A POST

B PUT

C GET

D DELETE

💡 Hint

Safe methods are used only to retrieve data without side effects.

GET is a safe method because it only retrieves data and does not modify any resource on the server.

🧠 Conceptual

intermediate

Which HTTP method is unsafe and used to update resources?

Unsafe methods can change server data. Which HTTP method below is unsafe and typically used to update an existing resource?

A GET

B HEAD

C OPTIONS

D PUT

💡 Hint

Updating means changing data on the server.

PUT is unsafe because it modifies or replaces the resource on the server.

❓ Predict Output

advanced

What is the output status code for a safe GET request?

Consider this HTTP request made to a REST API endpoint that returns data without changing anything. What is the typical HTTP status code returned?

Rest API

GET /api/items/123 HTTP/1.1
Host: example.com

A 200 OK

B 201 Created

C 204 No Content

D 400 Bad Request

💡 Hint

Successful GET requests usually return the requested data.

A 200 OK status means the GET request succeeded and the server returned the requested data.

❓ Predict Output

advanced

What error occurs if a DELETE method is sent to a read-only API?

If you send a DELETE request to an API that only allows safe methods, what HTTP status code will the server most likely return?

Rest API

DELETE /api/items/123 HTTP/1.1
Host: example.com

A 405 Method Not Allowed

B 200 OK

C 500 Internal Server Error

D 404 Not Found

💡 Hint

The server rejects methods it does not support.

405 Method Not Allowed means the server understands the method but refuses to allow it on the resource.

🧠 Conceptual

expert

Why are safe methods important for caching in REST APIs?

Safe methods like GET are often cached by browsers and proxies. Why is caching safe methods important in REST API design?

A Because safe methods always modify data, caching prevents repeated changes.

B Because safe methods do not change data, caching their responses improves performance without risk of stale data.

C Because unsafe methods are cached to reduce server load.

D Because caching safe methods causes data corruption.

💡 Hint

Think about how caching helps when data does not change.

Safe methods do not change data, so their responses can be cached safely to speed up repeated requests without causing incorrect data to be shown.